Throughout the campaign, Rubio has touted himself to conservatives as both the most electable GOP candidate (contestable, but likely true) and as the one best situated to reunite the warring factions of the broad right (undoubtedly correct). Nobody else in the field has the Florida senator’s enviable mix of skills and allies. He’s been a consummate compromise candidate, well-liked even by the overwhelming majority of Republican voters who favor other contestants. A canvas upon which basically every faction of the party, other than Donald Trump cultists, can paint its desires—the candidate of billionaire donors, neoconservative foreign-policy elites, the Republican operative class, and really of just about every point of influence within the party outside its nativist fringe. Even Rush Limbaugh has defended Rubio as “a legitimate, full-throated conservative.” Limbaugh was most recently spotted trying to pump life back into Rubio’s campaign, at the expense of his old horse Donald Trump, a day before the New Hampshire primary.

This unifying quality is a testament to the allure of electability over principle, and to the GOP’s desperate hunger not to lose a third consecutive presidential election. Before Saturday’s debate malfunction, it was Rubio’s greatest source of political power and the key to his prospects in the Republican primary. It was the reason why Rubio—the most doctrinaire Republican in the race—had even won over the support of reform conservatives, or “reformocons,” who have argued that the GOP cannot win the presidency without meaningfully altering its agenda.

Tuesday’s New Hampshire primary will test whether, by revealing the tissue-thinness of his political persona, Rubio has sacrificed his broad appeal. The answer will lie not just in the outcome of the primary, but in whether these elites rally to his side afterward or begin searching elsewhere.

Rubio has always been an odd fit for reform conservatives in particular. The reformocons argue that the Republican Party’s pre-Trump issue mix—supply-side fiscal policy, restrictive immigration policy, interventionist foreign policy, liberal trade policy, and conservative social policy—no longer enjoys majority support in the country. After 2012, most professional Republicans came to agree with this insight. But where GOP leaders (and Rubio, apparently) believed relaxing the party’s immigration platform would be the surest and most painless way to regain national majorities, reform conservatives—among them Ross Douthat, Reihan Salam, David Brooks, and David Frum—disagreed. They held that the party would be better off, and truer to modern conservatism, by adopting a more middle-class-friendly set of economic policies while stepping up immigration enforcement, especially with respect to low-skilled immigrants.

Why, then, have reform conservatives lined up behind Rubio? No major figure in today’s Republican Party perfectly reflects a reformist agenda, but at least a couple of candidates come much closer than Rubio—and one of them is extremely popular. There’s no credible way to argue that Donald Trump’s tax plan deviates from supply-side orthodoxy, but his economic views taken as a whole are much more solicitous of middle- and working-class interests than of the interests of business-class GOP donors, whose aims and tactics he regularly assails. Trump has turned the subtext of working-class white opposition to immigration into ugly text, but he comes closer to articulating the “reformocon” immigration critique than any candidate except perhaps Ted Cruz. Trump is leading in the polls. Were he more polished or (why mince words) better able to disguise his xenophobia, he would be a dream candidate for the reform movement. But he is an imperfect figure. So leading reform conservatives—though shaken by Saturday’s development—have enlisted their sympathies with Rubio.

The ironies abound. Whatever the opposite of reform conservatism is called, Rubio has become its patron saint. As the conservative writer and Rubio skeptic Michael Brendan Dougherty has patiently explained, “Rallying around Rubio [is] too strong a temptation for the GOP’s elite and the most established organs of the conservative movement [because] Rubio’s candidacy is essentially based on the premise that nothing from the George W. Bush era has to change for the Republican Party.”

The entire Republican Party is in thrall to supply-side economic doctrine, but Rubio is unique even in this regard. While every leading candidate proposes large, regressive tax cuts, Rubio alone proposes reforms (zeroed-out investment taxes, zeroed-out inheritance taxes, significantly reduced corporate taxes) designed to minimize (and in many cases eliminate) the tax liabilities of members of the Republican donor class. Though Rubio now disclaims his own immigration reform and amnesty legislation, he continues (when pressed firmly enough) to support eventually legalizing undocumented immigrants. He also wants to send ground troops into Syria and to generally reprise the country’s George W. Bush-era foreign policy doctrine.

If the GOP’s George W. Bush-era agenda no longer commands majorities, but Rubio is the electable Republican primary candidate, then his value proposition lies exclusively in his suddenly imperiled reputation as a messenger. Six years ago, Rubio described himself to Mark Liebovich of The New York Times Magazine in precisely those terms—as “a messenger for a set of ideas.” The content of those ideas has changed since then, asymptotically approaching the path of least resistance to the presidency, but until Saturday, the effectiveness of the message had only improved.

The question now is whether Rubio has fatally undermined his most compelling virtue as a candidate. Will he underperform in New Hampshire, and further demoralize his elite supporters—or will he dispel once and for all with the gospel that to be competitive in national elections, the Republican Party needs to change?

Brian Beutler is a senior editor at The New Republic. He hosts Primary Concerns, a podcast about politics.